In the middle and late stage of oilfield development, the dominant seepage channels lead to the increase of water cut and the decrease of oil production. The existing polymer profile control and flooding system is difficult to meet the requirements of high temperature, high salinity and low permeability reservoirs. In this paper, a new type of biopolysaccharide GP gum was developed, and its solution performance, gelling characteristics, injectability, fluid diversion ability and oil displacement effect were systematically evaluated. The results showed that GP gum was a sphingosine gum with novel structure. Its main chain contained 1→2, 1→4 and 1→6 glycosidic bonds. The monosaccharide composition was mainly glucose and guluronic acid, without rhamnose. It was significantly different from Willan gum and gellan gum. Its solution has the characteristics of "thermal viscosity increasing", and its temperature resistance and salt resistance are obviously better than xanthan gum. The viscosity retention rate is more than 50% at 100 ℃ and 71214 mg/L salinity. GP gum and organic chromium crosslinking agent can form high-strength gel. The gum forming strength under 2% crosslinking agent is more than 20000 MPa.s. The gum forming time is controllable and the strength is stable, which is much better than that of xanthan gum under the same conditions. The core injection experiment showed that the injection pressure of GP gum was low, and the viscosity retention rate after shear resistance was 83.9%, which was significantly higher than that of xanthan gum (63%) and HPAM (39%). In the dual pipe parallel core profile control and flooding experiment, the profile improvement rate reached 91.6% when the permeability difference was 5.47, and the diversion rate of low-permeability layer increased to 67.34%, with outstanding fluid diversion effect. The oil displacement experiment shows that the enhanced oil recovery of GP gum is 25.4%, the comprehensive oil recovery is 67.9%, and the oil displacement effect is significantly better than that of HPAM (9.6%) and xanthan gum (16.5%). GP gum provides a practical technical scheme for high-efficiency profile control and flooding in low-permeability, high-temperature and high salinity reservoirs, and the related achievements can provide an important reference for the popularization and application of biopolysaccharide in oilfield development.